Synchronous machine.



L. A. HAWKINS.

SYNGHRONOUS MACHINE.

APPLICATION TILED AUG. 5, 1909.

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WITZSZESSES' m 3\ Pym.

L. A. HAWKINS.

SYNGH'RONOUS MACHINE.

APPLICATION FILED AUG.5,1909.

Patented Mar. 15, 1910.

2 SHEETS-SHEET 2.

JNVENTUR LAURENCE A. HAWKINS.

UNITED STATES PATENT OFFICE.

' LAURENCE A. HAWKINS, 01 BCHENECTADY, NEW YORK, ASSIGNOR "10 GENERAL 1 ELECTRIC COMPANY, A CORPORATION OF vNEW YORK.

- srncnzaoivous Macnmn To all whom it mag concern:

Be it known that I, LAURENCE A. HAW- KINS, a citizen of the United States, residing at Schenectady, in the county of Schenectady and State of New York, have invented certain new and useful Improvements in Synchronous Machines, of which the followi is a specification.

y invention relates to synchronous alter nating current machines and its object is to devise a novel machine of this type, adapted for use either as a double current generator or as a frequency changer, in which the two voltages may be independently varied.

In accordance with my invention, the machine has only a single armature and single field magnet. The field coils which mechanicall form only a single winding are electrica ly connected in a plurality of circuits so as to produce two component. magnetomotive forces of different pole numbers, the relative strengths of which may be varied by varying the relative currents in the circuits in which the field coils are connected. The coils of the armature winding also are preferably arranged to form mechanically only a single'winding, but are connected in a plurality of circuits so as to form electrically two windings of difl'erent pole numbers corresponding to the pole numbers of.

the magneto-motive forces produced in the field magnet. If the pole numbers are so chosen as to be non-inductive with respect to each other, each component magnetomotive force of the field magnet induces a voltage in its own armature winding, and does .not affect the other armature winding. By varying the relative strengths of the two magneto-motive forces, the relative amounts of the induced armature voltages are varied. Thus the machine may be operated as a frequency changer with a constant voltage on the motor side, while the voltage on the generator side is varied through any desired ran e, or, if the machine is 0 erated as a dou 1e current generator, the v0 tage of both currents delivered may be varied, the-variation of each being independent of the other. While the armature coils are preferably arranged to form mechanically a single winding, my invention in' its broader aspect is not limited to this arrangement of armature winding.

inventionwill best be understood by fiieciflcation or Letters ZEatent.

Application flied August 5, 1909. Serial No. 511,324.

minals of one armature circuit.

Patented Mar.

reference to the accompanying drawings, in whicha I Figure 1 shows diagrammatically a ma chine arranged in accordance with my inventlon, both field and armature being shown as developed on a plane surface, and Figs. 2 and 3 show modifications of the arrangement of field winding.

In Fig. v1, A A A and A represent armature coils or groups of armature coils. I have indicated only a single-phase winding, but it will be understood that my invention is applicable to a machine having any number of phases. a a represent the ter- It will be seen that this circuit extends through the four groups of-coils in two parallel circuits. one comprising the coil groups A and A and the other the coil groups A and A If the momentary direction of the current at the terminals is as indicated by the arrow heads, the current directions in the coil conductors will be as indicated by the heavy or upper arrow heads applied to the coils. It will further be seen, from this current distribution, that the armature winding, so far as this circuit is concerned, is an eight-pole winding. a 11. represent the terminals of the second armature circuit. One of these terminals is connected to the junction be- 1 tween the coil groups A and A and the oAther terminal to the junction of coils A and 4 equipotential points with respect to the eight-pole circuit having the terminals a a. This second circuit, of which the terminals are represented at a a is a parallel circuit in the armature winding, the coil groups A and A forming one path and A and A the other. rent-at terminals a is as represented by the arrow heads, the current in the armature coils for this circuit will be as indicated by the light or lower arrow heads. seen from the current distribution that so far as this circuit is concerned, the armature in series across the terminals of'an exciter C. These (20118 are connected so as to make these alternate poles all of the same polarity, as indicated by the letters .9 applied to them.

It will be That is, these terminals a a are at If the momentary direction of our-- The intermediate poles F F etc. consequently have an opposite polarity due to these coils, as represented by the letters n in heavy lines. The coils which are thus connected directly across the terminals of the exciter consequently produce an eightpole magneto-motive force in the field magnet which acts upon the armature circuit, whose terminals are at a a and has no efi'ect on the other armature circuit, since the voltages induced in each of its parallel parts by this eight-pole magnetization have a resultant value of zero. On the other poles F F etc. are placed a second series of coils which are connected to the eXciter C through a rheostat D. As long as no current is flowing through this second set of field coils, no voltage is induced at the armature terminals a \Vhen', however, current is supplied to these coils, a second magneto-motive force is produced in the field magnet having the olarities indicated by the letters 71 s in light ines. It will be seen that this magnetomotive force is four-polar and strengthens the eight-polar magnetization in poles F and F, while weakening it in alternate poles of the same polarity, that is, in poles F and F The other poles F F etc., are unaitected. The four-polar magnetization induces a voltage in the armature circuit having its terminals at a a and the amount of this voltage may be varied by means of the rheostat D without afiecting the voltage induced in the armature circuit having its terminals at a a It will be seen that only half of the polar projections of the field magnet are used for the four-pole magnetization in Fig. 1. This means that the armature copper is not utilized so efi'ectively for the four-pole circuit as for the eight. By the arrangement of Fig. 2 all of the polar projections of the field magnet are used for the four-pole magnetization, as well as for the eight-pole. In this fi ure each circuit includes part of the coil 0? each field pole, the relative connections of the coils being as shown. The eightole magnetization is the same as in Fig. 1, ut for the four-pole magnetization two field poles F F, for instance, constitute a single magnetic pole. As in Fig. 1, the volta e induced in one armature circuit may e varied by means of the rheostat D without varying the voltage induced in the other armature circuit. The arrangement of Fig. 2 as compared with that of Fig. 1 utilizes the armature copper to better advanta e, but does not utilize the field copper so efliciently. For instance, the currents in the two halves of the coils on certain poles, as F F, F 5 and F are in opposition with respect to their magneto-motive forces, and therefore there exists at these poles an unnecessary C2R loss.

Still other arrangements of the field coils only every other pole is wound, all the maybe employed; for instance, in Fi 3 eld copper being concentrated on the four poles F 2 F F and F. E represents a resistance adapted to be connected in shunt to a portion of the field coils. As long as the resistance E is open circuited, there exists only an eight-pole magnetization, but when, however, the circuit of the resistance is closed as indicated in dotted lines and the contact 6 moved toward its dotted line position so as gradually to short circuit the resistance E, the current in field poles F and F is increased so as to strengthen these poles as indicated by the letters n in light lines, while the current in poles F and F is decreased so as to weaken their magnetization as indicated by the letters .9 in light lines. When the contact 6 has reached the dotted line position no current is flowing through the coils F and F while the current in the coils on the poles F and F has been doubled. There are then, in effect, only two active field coils, but .these are so placed as to give the equivalent of eightpolar and four-polar magneto-motive forces existing simultaneously and inducing voltage in both armature circuits.

Other arrangements of field coils may be employed, and also other arrangements of armature coils than that shown. It is only necessary, if the mechanically single armature winding is employed for both circuits, that the coils be so connected that the two circuits shall be mutually non-inductive.

It should be noted that if the smaller number of poles were made less than four, the machine would be magnetically unbalanced and strains would be produced in the shaft. For this reason the numbers of poles should not be less than eight and four, thouigh they may be as much greater as desire I do not desire to limit' myself to the arrangements and connections of parts shown and described, but aim, in the appended claims, to cover all modifications which are within the scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. A synchronous alternating-current machine, having a single armature and a single vfield magnet, each having coils forming mechanically a single winding but connected in a plurality of circuits and thereby forming electrically two windings of different pole numbers, and means for supplying to two circuits of the field magnet currents relatively variable in amount to induce relatively variable voltages in two armature circuits respectively.

2. A synchronous alternating current machine having a single armature and a single field magnet, said armature havin coils forming mechanically a single winding but connected .111 a p ura thereb formin w v of 'di erent po eii members, said fi d magnet havin coils:a'nd'i'connections'jfor pro ducing in sai magnet 'simultaneously; two; component gma etc-motive, forces. cone-.- sponding inifjpo eg numberxto the two-pole; numbers of}the;arrnature winding,,* and' means for varying'fthe? relativestrengths: of said magneto-motive'forces to vary the.r e'la-- tive amounts of} thewoltages' induced :t-liearmature "circuitsi 3. "A synchronous alternating current niachine having a sm 1e armature and a smgle field magn et, sai armature having COIlS v forming mechanically a, single windmgbut different pole numbers an connected in a luralit thereby forminge ectrica 1 two windings of d said field magnet having coils andconnections for producing in sa1d magnet amagneto-motive force corresponding in pole number to. the greater pole number of the armature, and means for v varying. the relative strengths of poles of the same polarity in the field magnet to V produce therein a secondcomponent ma number to the lesser pole mum in pole number .to the greater'pole number.

of the armature, and means for varying the of circuits and *relative-strengths, of alternate poles of the samepolarity 1n the field magnet. to produce vth'er'em' a second component magneto-motive -force eorrsspondingflm {pole number to the lesser polenumber of the armature.

5.";Asynchronous alternating current ma chine-;haging;aisingle armature and a single fie'ld magne said armaturehaving coils and connectionsiformin ,electrically two windings of-difierentipo e numbers and said field. In:

P a two component magneto-motive forces cora a ro icing; m said magnetl=simultaneously responding in pole numbers respectively to the two. pole numbers of the armature and means for varying the relative strengths of said magneto-motive forces to vary the rela- I I t-ive amounts of the voltages induced in the armature circuits.

6. A synchronous alternating current maeer havi'ng. coils and connections for chine having a single armature and a single I field magnct,sa1d armature havmg coils and 7 connections forming electrically two, windings of difi'erent po e numbers and said field magnet having coils and connections for producing in said magnet a magneto-motive orce corresponding in pole number to the greater. pole number of the armature, and means for varying the relative stren the of poles of the same polarity in the fiel magnet to produce therein a second component magneto-motive force corresponding in pole number to the lesser pole number of the armature.

In witness whereof, I" have hereunto set my hand this 4th day of August, 1909.

LAURENCE A. HAWKINS.

Witnesses:

' BENJAMIN B. HULL, I

Mammal E.; Woonnar; 

